#include <stdio.h>
#include <string.h>

void reverse(char *);

int main() {
    char str[] = "123456789";
    int c, i;
    i = 0;
    
    reverse(str);
    printf("%s", str);
    return 1;
}

void reverse(char *s) {
    int len = strlen(s);
    char tmp;
    printf("%d", len);

    for (int i = 0; i < len/2; i++) {
        tmp = s[i];
        s[i] = s[len - i - 1];
        s[len - i - 1] = tmp;
    }
}